Gallic Empire

The Gallic Empire was a breakaway part of the Roman Empire which existed from 260 to 274 AD, with Colonia Agrippina (Cologne) serving as its capital (later replaced by Augusta Treverorum/Trier in 271). It was established by Postumus in 260 in the wake of barbarian invasions and instability, and he established autonomy in the provinces west of the Alps. His empire had its own Praetorian Guard and elected its own Consuls and its own Roman Senate, and it was backed by the might of multiple foederati tribes. After Postumus' assassination in 268 it lost much of its territory, and it was retaken by the Roman emperor Aurelian in 274 AD after he defeated Tetricus I at Chalons.